An automobile is provided with front and rear bumper beams in the front and rear part of a vehicle body, respectively, and the front and rear bumper beams are configured so as to deform and absorb an impact when an impact has acted on the front bumper beam or the rear bumper beam, and the vehicle occupants are protected by the absorption of the impact.
Front and rear bumper beams are provided with an impact-cushioning member for reducing an impact that acts on objects with relatively low rigidity when the automobile has collided with an obstacle (object) having relatively low rigidity. Such an impact-cushioning member is disclosed in Japanese Patent Laid-Open Publication No. 2004-114864 (JP 2004-114864 A).
The impact-cushioning member will be described below using the front bumper, selected from the front and rear bumper beam, as a bumper beam.
The impact-cushioning member is disposed along the lengthwise direction in the front surface of the bumper beam, and the cross-sectional shape is designed so as to deform under a relatively small impact.
The cross-sectional shape is designed so as to deform under a relatively small impact, whereby the impact-cushioning member deforms and cushions an impact that acts on an object having relatively low rigidity when the automobile has collided with an object having relatively low rigidity
However, it is difficult to determine the cross-sectional shape of the impact-cushioning member so that impacts that act on objects having a relatively low-rigidity are cushioned.
The impact-cushioning member is preferably also used to reduce impacts on vehicle occupants, as well as cushioning impacts against objects having relatively low rigidity.
However, it is even more difficult to determine the cross-sectional shape of the impact-cushioning member so that the impact-cushioning member can be used to reduce impacts on objects having relatively low rigidity and to also reduce impacts on the vehicle occupants.
Japanese Patent Laid-Open Publication No. 10-217880 (JP 10-217880 A) discloses an impact-cushioning member in which a helically wound impact-absorbing tube is bonded and fixed to the side portion of an impact-absorbing pad, whereby impacts are absorbed first by the impact-absorbing tube alone when an impact has occurred, and the impact is absorbed midway during the impact by the impact-absorbing tube and the impact-absorbing pad.
The impact-absorbing tube uses an aluminum core element together with a soft material and is formed by helical winding. The impact-absorbing pad is composed of a foaming agent.
The impact-cushioning member of JP-A-10-217880 has an impact-absorbing tube that is bonded and fixed to the side portion of an impact-absorbing pad, and is therefore more capable of absorbing impacts in comparison with the impact-cushioning member of JP 2004-114864 A.
The impact-cushioning member of JP 10-217880 A is believed to be capable of relatively easily reducing an impact with an object having relatively low rigidity as well as reducing an impact on vehicle occupants when the member is provided to the front surface of the bumper beam.
As described above, the impact-cushioning member of JP 10-217880 A combines the use of an impact-absorbing tube and an impact-absorbing pad in that the impact-absorbing tube is bonded and fixed to the side portion of the impact-absorbing pad. For this reason, the impact-cushioning member has a relatively large shape and is difficult to provide to the bumper beam. Also, the member must be separately provided, and improvement is still needed in terms of assembly and manufacturing costs.